DESCRIPTION: The PI will continue to study molecular controls of apoptosis in Drosophila. The reaper gene, which was shown by the PI to have a central role in initiation of apoptosis, will be used in a dosage sensitive manner to conduct genetic screens for other cell death genes in Drosophila. In preliminary work, chromosomal deletions and point mutations have been recognized which enhance or suppress reaper derived cell death. In the proposed work: (1) Such screens will be extended in an effort to collect effector genes. These should encode functions responding to reaper expression and responsible for providing specific elements of the cell death machinery. (2) Effector genes will be cloned and characterized at the molecular level. (3) Phenotypes of loss of function mutations at effector loci will be examined independent of modulation of reaper to better understand the role of each gene in control of cell death.